Laravel 5 Querying with relations causes "Call to a member function addEagerConstraints() on null" error

php mysql laravel laravel-5 eloquent

59,919

Solution 1

You are missing return statements in the methods that define relations. They need to return relation definition.

Replace

public function roles()
{
    $this->belongsToMany('\App\Role', 'fk_user_role', 'user_id', 'role_id');
}

With

public function roles()
{
    return $this->belongsToMany('\App\Role', 'role_user', 'user_id', 'role_id');
}

Solution 2

You forgot the return in your functions

Do:

return $this->belongsToMany('\App\User', 'fk_role_user', 'role_id', 'user_id');

return $this->belongsToMany('\App\Role', 'fk_user_role', 'user_id', 'role_id');

Solution 3

You need to use Return for your function's result. If you do not do that, Laravel does not know What should do with that function without any action. Just use like this

return $this->hasOne(xxx, xx, xx);

Enjoy your coding !

Solution 4

Make sure you have written return in your model function relation.

return $this->hasMany('App\StaffShift','user_id','user_id');

View more solutions

59,919

Author by

Tomkarho

Updated on June 08, 2021

Comments

Tomkarho almost 3 years

I have been trying to create a simple user management system but keep on hitting road blocks when it comes to querying relations. For example I have users and roles and whenever I try to make a query for all users and their roles I get an error. The one in the title is only the latest one I've encountered.

My User and Role Models look like this:

class Role extends Model
{
    public function users()
    {
        $this->belongsToMany('\App\User', 'fk_role_user', 'role_id', 'user_id');
    }
}

class User extends Model
{
    public function roles()
    {
        $this->belongsToMany('\App\Role', 'fk_user_role', 'user_id', 'role_id');
    }
}

My migration table for many-to-many relationship between the two looks like this:

public function up()
    {
        Schema::create('role_user', function (Blueprint $table) {
            $table->increments('id');
            $table->integer('user_id')->unsigned()->nullable(); //fk => users
            $table->integer('role_id')->unsigned()->nullable(); //fk => roles

            $table->foreign('fk_user_role')->references('id')->on('users')->onDelete('cascade');
            $table->foreign('fk_role_user')->references('id')->on('roles')->onDelete('cascade');
        });
    }

And then I try to get all records with their relation in a controller:

public function index()
{
    $users = User::with('roles')->get();

    return $users;
}

So I need another pair of eyes to tell me what is it I am missing here?

Tomkarho almost 9 years

Also for anyone else reading this with the same problem I needed to fix the second parameter from "fk_user_role" to "role_user".
Jorn over 7 years

I'm going to kill myself now :P hours wasted, at least now I will never forget
Reem Aziz over 6 years

same problem as me, spend hours to solve stupid mistake thank you
Mr.Thanks about 6 years

It's frustrating, it's just not returning
Istiaque Ahmed over 5 years

may I ask you to have a look at a Laravel join related question at stackoverflow.com/questions/52149031/… ?
Agil almost 5 years

That is absolute madness :D
Jose Mhlanga over 4 years

This is correct. Faced this for a long time without noticing it. Relationships in eloquent are returned by the model when u call the relationship method in calling class. Thanks
Floris about 4 years

OMG this was it.
Ruhith Udakara about 4 years

I feel so dumb, hours wasted
shahsani over 2 years

yes yes, this is what I forgot to write in my relation function. thanks a bunch @Leonel!
Bart Mommens almost 2 years

every single time i forget that return, <3 thanks ;)
Enver almost 2 years

That's normal, We are all doing that generally. :) You r welcome !